Remove unused node selector functions & legacy environment variables

[Sovietaced]

Why are the changes needed?

This pull request removes some code that was not used which simplifies the codebase. It also removes extraneous environment variables that are injected into Flyte task containers, which has been confusing for me.

What changes were proposed in this pull request?

Removes code and removes legacy environment variables.

How was this patch tested?

Unit tests and in our production environment.

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Summary by Bito

This pull request enhances code clarity by removing unused node selector functions and legacy environment variables from Flyte task containers. The cleanup simplifies the codebase and reduces confusion, with updated unit tests ensuring stability and correctness.

[flyte-bot]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.56%. Comparing base (890d564) to head (cd577cb).
⚠️ Report is 15 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6614      +/-   ##
==========================================
- Coverage   58.59%   58.56%   -0.03%     
==========================================
  Files         929      929              
  Lines       70851    70876      +25     
==========================================
- Hits        41513    41512       -1     
- Misses      26192    26211      +19     
- Partials     3146     3153       +7     

Flag	Coverage Δ
unittests-datacatalog	59.03% <ø> (ø)
unittests-flyteadmin	56.13% <ø> (ø)
unittests-flytecopilot	40.87% <ø> (+1.31%)	⬆️
unittests-flytectl	64.64% <ø> (ø)
unittests-flyteidl	76.12% <ø> (ø)
unittests-flyteplugins	61.01% <ø> (-0.10%)	⬇️
unittests-flytepropeller	55.06% <ø> (ø)
unittests-flytestdlib	63.05% <ø> (-0.06%)	⬇️

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[flyte-bot]

Bito Automatic Review Skipped - Draft PR

Bito didn't auto-review because this pull request is in draft status.
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[Sovietaced]

I validated that the SDK no longer uses these.